Without limiting the scope of the invention, its background is described in connection with an optic based sensor system using a diverse collection of lenses, filters, detector and light components and related electronics to detect, qualify and quantify the presence of one or more sample analytes.
Optic-based sensor systems have been developed and used in the fields of chemical, (bio)chemical, biological or biomedical analysis, process control, pollution detection and control as well as others. A typical application involves the chemical coating of a thin film, cable or other article followed by excitation and measurement in the presence of a given sample of interest.
The earliest prior art systems combined a wide assortment of lenses, filters, light sources, detector component and electronics. One example is the fluorescence-based fiber optic oxygen cable sensor which uses a single high brightness Light Emitting Diode (LED) to produce an excitation signal that catalyzes the emission properties of the fluorescence coating material which interacts with the analyte sample of interest to produce a measurable difference in the emission. The material is deposited on a length of the fiber optic cable which, in turn, is emersed in the sample solution producing a measurable change in the fluorescence chemistry emission.
Another prior art system uses a prism shaped lens to direct light incoming one surface onto a second surface upon which a sample reagent or binding material has been deposited. The second surface is placed in contact with the sample which binds to or otherwise interacts with the reagent to alter the angle of refraction along the prism/sample interface. The light output is directed out the third prism surface towards a detector array that senses the angular change indicating one or more sample properties.
These earlier sensor systems had limited use in most practical field applications. The signal generator, LED, lens, filter, detector, amplifier and other components required significant amounts of work space to setup and operate. In addition, their overall high cost and immobility confined their use to the laboratory and research environment. Moreover, such systems required specialized and routine maintenance to ensure precise alignment of the optics in relation to the light sources, detector components and other sub-systems.
Recent advances in miniaturized low powered light sources and detectors has allowed the design of compact fully integrated sensors. A main feature of these miniaturized sensors is the fixed positioning of the light source, sampling surface and detector elements within a rigid solid housing. Thus, miniaturized sensors eliminate the need to transport the sample to the sensor sampling surface. Because the components are readily available the miniaturized sensors are easier to maintain and less expensive to manufacture. Also, since the optics are fixed, miniaturized sensors do not exhibit the same alignment problems of the bulkier prior art sensor systems.
Until the present invention, however, the use of the miniaturized integrated sensors in application specific hand held instruments has not been contemplated. A device that communicates with one or more sensors which are in close proximity or contact with the sample would permit distributed monitoring of environmental conditions and provide great utility.